Well drilling device

ABSTRACT

A drill bit comprising a body wherein is provided a chamber including a Venturi passage in communication with an ejector located below the Venturi passage, this assembly being located close to the working face of the bit which is in contact with the well bottom. The chamber is connected at its lower part to said working face through duct means and is connected at its upper part to the annular space between the wall of the well and the drill bit. The ejector is connected with a flushing fluid supply so as to produce an upwardly directed flow of fluid through the chamber and a negative pressure is thus created in said chamber with respect to the fluid pressure at the level of said working face. The cuttings are lifted through said duct means as a result of said negative pressure and flow through the chamber in the same direction as the flushing fluid flowing from the ejector. Means may be provided for reversing when desired the direction of flow of the flushing fluid on the working face of the bit.

United States Patent [191 Tiraspolsky WELL DRILLING DEVICE Wladlmlr Tlraspolsky, lssy Les Moulineaux, France [73] Assignee: Institut Francals Du Petrole, Des

Carburants Et Lubrlflants, Rueil-Malmaison, France [22] Filed: May 28, 1971 [21] Appl. No.: 148,066

[75] lnventor:

[30] Foreign Application Priority Data 1 July 3,1973

Primary Examiner-James A. Leppink Attorney-Craig, Antonelli & Hill [5 7] ABSTRACT A drill bit comprising a body wherein is provided a chamber including a Venturi passage in communication with an ejector located below the Venturi passage. this assembly being located close to the working face of the bit which is in contact with the well bottom. The chamber is connected at its lower part to said working face through duct means and is connected at its upper part to the annular space between the wall of the well and the drill bit. The ejector is connected with a flushing fluid supply so as to produce an upwardly directed flow of fluid through the chamber and a negative pressure is thus created in said chamber with respect to the fluid pressure at the level of said working face. The cuttings are lifted through said duct means as a result of said negative pressure and flow through the chamber in the same direction as the flushing fluid flowing from the ejector. Means may be provided for reversing when desired the direction of flow of the flushing fluid on the working face of the bit.

7 Claims, 5 Drawing Figures PAIENIEDJUL3 ma sum 1 or z new new A d b 6 Hell WELL DRILLING DEVICE This invention relates to the drilling of wells, making use of a negative pressure, the efficiency of which is particularly high, and to a device therefor.

This device, according to the invention, whereby the drilling efficiency is substantially increased, comprises a bit body, at least one working face thereof delimiting the well bottom, and means for providing, in a zone of said bit body, a negative pressure with respect to the pressure prevailing at said working face, in combination with at least one lifting duct for the ground cuttings, connecting said working face with said zone of negative pressure, at least one discharge duct for the flushing fluid, passing through said zone of negative pressure and opening into the annular space between the drill string and the wall of the drilled well, through at least one orifice located outside said working face, and means for limiting the flow rate of the flushing fluid between said orifice of said discharge duct and said working face.

This device is remarkable in that said means for creating the negative pressure comprise the combination of a Venturi and an ejector both in the vicinity of the working face, said ejector being located below the Venturi and being fed with an ascending stream of flushing fluid having the same flowing direction as the cuttings reaching the zone of negative pressure through said lifting duct.

According to a preferred embodiment of the invention, whereby the well bottom can be fed with flushing fluid having a low content of cuttings, the device comprises, downstream from the Venturi with respect to flowing direction of the flushing fluid, means for dividing the stream thereof to a first portion which is discharged from the bit body through at least one first orifice located above a shoulder of the bit body, said first stream portion raising up to the surface entirely and a second stream portion which is discharged from the bit body through at least one second orifice opening at a lower level than said first orifice, at least one part of said second stream portion being discharged downwardiy to the well bottom, said dividing means being adapted to reduce the cuttings content of the fluid stream portion flowing through said second orifice by directing the major part of the cuttings contained in the stream towards the first orifice.

These dividing means may, for example, comprise a separation chamber of the cyclone type and a deflector member entrancing the effect of the centrifugal force.

It is an object of the present invention to provide a drill bit of the contemplated type, comprising a device whereby there can be performed successively a drilling step with a centripetal irrigation followed with the restoration of a conventional centrifugal irrigation without necessitating the pulling out of the drill bit.

According to a specific embodiment of the invention the reversal of the fluid direction is achieved by introducing into the drill string a ball which comes in abutment onto a seat arranged in the head of a distributing piston axially set in position by means of shear pins, thereby obturating the passage ways for the drilling mud.

As a result of the overpressure due to the obturation of said mud passage ways, the pins are sheared and the distributing piston is moved to a position at which the Venturi is blocked and the orifices are uncovered through which the fluid directly flows towards the drill bit center.

In order that this invention may be more fully understood some non-limitative embodiments in accordance therewith will now be described by way of example with reference to the accompanying drawings wherein:

FIG. 1 shows an axial cross section of a first embodiment.

FIG. 1 A is a view from above of a cross section along plane A-A of the device illustrated in FIG. 1.

FIG. 1 B is a partial perspective view of the deflector.

FIG. 2 is a partial view illustrating a modification of the embodiment of FIG. 1.

FIG. 3 shows a particular embodiment of a device for switching from a centrifugal flow of the flushing fluid to a conventional centrifugal flow.

In the illustrated embodiment, the device comprises a drill bit body 1 with a solid head, said bit body being coupled at its upper part, through a head connector I d, to a rotary element 1 a which may consist of a drill string driven in rotation from the surface (so'called rotary drilling method) or of a stern driven by a bottom motor (turbine or electric motor).

The flushing fluid flows from the surface along the path shown by the arrows and irrigates the bit and the well bottom delimited therewith.

The fluid feeds, through ducts 1 b, the annular groove 3 b and the duct 3 c, an ejector 3 being provided for cooperation with a Venturi 4, in line therewith, so as to create a negative pressure in chamber 5 inside the bit body, said chamber being connected to the negative pressure zone of the bit working face. The ejector 3 is mounted on a support member 3 a.

The negative pressure generated in chamber 5 by the flowing of the flushing fluid results in a suction of the ground cuttings from the well bottom through ducts 10 for the cuttings upraise (only one duct is shown in FIG. 1

These ducts establish the communication, through one or more orifices, between chamber 5 and the well bottom.

The flow of these cuttings is shown by double arrows on FIG. 1.

By the provision, according to this invention, of a negative pressure chamber 5 in the vicinity of the working face of the bit head, the length of the ducts 10 connecting said chamber with the well bottom, can be reduced, thereby increasing the suction of the cuttings and accordingly the drilling efficiency.

Moreover the ejector 3 is so arranged according to this invention that the fresh flushing fluid (not charged with cuttings) passes upwardly therethrough, thereby providing for the entrainment with the fluid flow of the cuttings raising up from the well bottom through ducts 10, without reversal, at the length of the ejector, of the flowingdirection of said cuttings.

Such an arrangement makes easier the discharge of the cuttings from the well bottom.

The fluid stream, charged with the cuttings, which raises up through the Venturi 4 is divided in two portions.

The first one is discharged through ducts 6 opening through outlets 6 a into the annular space 7, between the bit body and the well wall, above an annular shoulder 1 c of connector 1 d, in a part of reduced section of connector I d.

The other portion of the fluid stream is discharged through outlets 6 b provided below the shoulder I c.

The ratio of the fluid flow rates respectively through outlets 6 a and 6 b as well as the distribution in upward and downward streams of the fluid flowing through outlet 6 b can be adjusted by conveniently selecting the ratio of the respective sections of outlets 6 a and 6 b, the ratio of the annular passageways for the flushing fluid provided respectively above and below the shoulder 1 c, the height of the lateral surface of the bit head in contact with the well bottom, the width of the working surface in contact with the wall bottom, and the number and the section of the ducts which may be provided on said two surfaces for giving passage to the flushing fluid towards ducts 10 for the cuttings upraise, i.e., briefly, by adjustment of the means for limiting the flushing fluid flow rate between the outlet 6 b for the flushing fluid and the working face of the bit head 2.

A part of the fluid stream is discharged through outlets 6 b is thus recycled to the well bottom and flows downwardly along the well wall in the direction shown by the arrows, while the part of the fluid stream discharged through outlets 6 a in an enlarged zone of the annular space surrounding the bit raises in totality up to the ground surface.

According to a particular embodiment of the invention, the bit is provided with means for insuring a greater proportion of cuttings in the fluid stream portion discharged through outlets 6 a and raising up to the ground surface than in the stream portion recycled to the well bottom through outlets 6 b.

Said means may, for example consist, as illustrated in the drawings, of a centrifugation chamber or cyclone 21 in which the swirling motion may be activated by a device Such as the vane carrying ring 20, shown in a perpsective view in FIG. 1 b.

This swirling motion deviates the cuttings contained in the flushing fluid towards outlets 6 a through which said cuttings flow towards the ground surface, while the part of the fluid stream, which is close to the axis of the device and consists of a purer flushing fluid, is discharged through outlets 6 b and irrigates the well bottom.

As above indicated, the respective flow rates through outlets 6 a and 6 b are controlled by adjusting the sections and pressure drops, so that the flow rate of fluid purified by the vortex" 21 be greater than the flow rate sucked by the bit towards the wall bottom, thereby protecting the same against a downward motion of the cuttings.

FIG. 2 partly illustrates a modification of the embodiment of FIG. 1. As shown on said figure, in order to activate the centrifugal action resulting in the purification of the central part of the fluid stream flowing in the Venturi, the fluid stream feeding the ejector is caused to rotate by offsetting the feeding duct 3 c. The swirling motion of the fluid stream feeding the ejector makes the device unnecessary.

FIG. 3 shows a device for switching the direction of the flushing fluid stream in a bit of the negative pressure type, for restoring a conventional centrifugal irrigation of the well bottom.

By experience it has been observed that, in some cases, it is of interest to restore a conventional centrifugal irrigation of the well bottom, particularly when the negative pressure generates undesired effects in the rock, e.g., activation of fluid effluence, or when a technical difficulty occurs such as a jamming, the need of a substantial redrilling and the like.

It is advantageous to provide means for reversing at will the direction of the fluid flow so as to obtain the best drilling conditions: drilling with negative pressure or conventional drilling with centrifugal irrigation without the need of pulling out and changing the drill bit.

The reversing device is placed inside the head connector l d of the bit of the negative pressure type. In this connector is placed a centrifugation chamber 21 which is axially isolated from the irrigation stream coming from the drill string 1 a through the distributing piston 23. Said piston comprises a cylindrical part 24 provided with a recessed hole 25 and a head 26 of larger diameter in which is arranged a seat 27, the head 26 being slidabie in the bore of connector I d.

Inclined channels 28 across the head 26 of the distributing piston 23 interconnect the recessed hole 25 and a slot 29 provided in the lateral surface of the distributing piston head 26, joints 30 insuring a sealing on the two sides of the slot 29.

Further a channels 31 across the head 26 of the distributing piston 23 interconnect the seat 27 and the annular space 32 formed between the connector 1 d and the external surface of the cylindrical part 24 of the distributing piston, the ducts 1 b opening at the lower part of the annular space 32, as shown in the figure.

During the step of drilling with a centripetal irrigation of the well bottom (negative pressure drilling), the distributing piston 23 is held in the position shown on the right-hand side of FIG. 3 by means of circlips 33 preventing any upraising of the distributing piston and through pins 34 which make the cylindrical part 24 solid with a ring 35 housed in the bore of connector 1 d, whereby any downward motion of the distributing piston is prevented.

The flushing fluid then flows from the drill string 1 a towards ducts l b, along the path shown by the arrows in solid line on the right-hand part of the figure, i.e., through the seat 27, the channels 31 and the annular space 32. The operation is the same as indicated with reference to FIG. 1.

When it is desired to obtain a fluid flow with a conventional centrifugal irrigation of the well bottom, a ball 36 is introduced into the drill string and comes in abutment against the conical seat 27, thereby interrupting the flushing fluid flow. The pressure of the flushing fluid then exerts on the distributing piston 23 a downwardly directed axial thrust which causes the shearing of the pins 34 and the subsequent lowering of the distributing piston to the position shown on the left-hand side of the figure.

The flushing fluid then flows along the path shown by the arrows in dashed line, i.e., from the drill string to the bit center through channels 31, the recessed hole 25, the venturi 4 and the ducts 10, before raising up through the annular space 7 between the wall of the drilled well and the bit.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of the invention and, without departing from the spirit and scope thereof can make various changes and modifications of the invention to adapt it to various usages and conditions.

By way of example, when required by the size of the bit, the distributing piston 23 can be given such a shape that, in the drilling position with conventional centrifugal irrigation of the well bottom, it obstructs the orifices of ducts l b opening in the connector 1 d.

There could be also provided a fishing device for the ball 36 and the shear pins could be replaced by resilient device such as a calibrated spring for the switching from the position of negative pressure drilling to the conventional drilling with centrifugal irrigation of the well bottom and vice-versa.

Such changes as well as others are consequently within the full range of equivalence of the following claims.

What I claim as my invention is 1. A well drilling device comprising a bit body having at least one working face for engaging with the well bottom, a negative pressure chamber inside said body, said chamber including means for creating a negative pressure with respect to the fluid pressure at the level of the working face, in combination with at least one lifting duct for raising the drilled cuttings and connecting said working face to said chamber, at least one discharge duct for the flushing fluid passing through said chamber and opening in the annular space between the drill string and the wall of the drilled well through at least one orifice located apart from said working face, and means for limiting the flow rate of the flushing fluid between said orifice of said discharge duct and said working face, wherein said means for creating the negative pressure comprises the combination of a Venturi and an ejector located in the vicinity of the bit working face, said ejector being placed below the Venturi so as to be fed with an upward stream of flushing fluid in the same direction of flow as the cuttings reaching said chamber through said lifting duct.

2. A well drilling device according to claim 1, wherein there is provided, downstream from the Venturi with respect to the direction of flow of the flushing fluid, means for dividing said fluid flow into two portions, the first of which being discharged from the bit body through at least one first orifice provided above a shoulder of said bit body, the entirety of said first flow portion raising up to the ground surface and the second portion being discharged from the bit body through at least one second orifice opening at a level lower than that of said orifice, at least one part of said second flow portion moving downwardly towards the bit to the well bottom.

3. A well drilling device according to claim 2, wherein said means for dividing are adapted to lower the cuttings content of the flow portion discharged through said second orifice and to direct the major part of the cuttings contained in the fluid stream towards said first orifice.

4. A device according to claim 3, wherein said means for dividing comprise deviating means enhancing the action of the centrifugal force produced by the rotation of the bit.

5. A device according to claim 1, comprising the combination of a distributing piston axially isolating said Venturi from the flushing fluid flow, said piston comprising a first series of channels communicating, in a first position of said piston, with feeding ducts for said ejector and a second series of channels which, in a second position of said piston, directly interconnect said Venturi, at the upper part thereof, with the feed of flushing fluid, the switching from said first to said second position being controlled by means for obstructing the channels of said first series.

6. A device according to claim 5, in which said means for obstructing the channels of said first series consists of a ball placed into the drill string.

7. A device according to claim 3, wherein said means for dividing comprises means adapted to feed said ejector with a stream of flushing fluid having a swirling motron.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 743, 035 Dated July 3, 1973 Inventor s) Wladimir Tiraspolsky It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title page, insert the following:

[30] Foreign Application Priority Data June 3, 1970 France 70/20472 (SEAL) Attest:

C. MARSHALL DANN MCCOY M. GIBSON JR.

Commiss ioner of Patents At tes t ing Off icer FORM Do-1050 (10-69) USCOMM'DC 60376-P69 U.S. GOVERNMENT PRINTING OFFICE: I969 0-366-334 

1. A well drilling device comprising a bit body having at least one working face for engaging with the well bottom, a negative pressure chaMber inside said body, said chamber including means for creating a negative pressure with respect to the fluid pressure at the level of the working face, in combination with at least one lifting duct for raising the drilled cuttings and connecting said working face to said chamber, at least one discharge duct for the flushing fluid passing through said chamber and opening in the annular space between the drill string and the wall of the drilled well through at least one orifice located apart from said working face, and means for limiting the flow rate of the flushing fluid between said orifice of said discharge duct and said working face, wherein said means for creating the negative pressure comprises the combination of a Venturi and an ejector located in the vicinity of the bit working face, said ejector being placed below the Venturi so as to be fed with an upward stream of flushing fluid in the same direction of flow as the cuttings reaching said chamber through said lifting duct.
 2. A well drilling device according to claim 1, wherein there is provided, downstream from the Venturi with respect to the direction of flow of the flushing fluid, means for dividing said fluid flow into two portions, the first of which being discharged from the bit body through at least one first orifice provided above a shoulder of said bit body, the entirety of said first flow portion raising up to the ground surface and the second portion being discharged from the bit body through at least one second orifice opening at a level lower than that of said orifice, at least one part of said second flow portion moving downwardly towards the bit to the well bottom.
 3. A well drilling device according to claim 2, wherein said means for dividing are adapted to lower the cuttings content of the flow portion discharged through said second orifice and to direct the major part of the cuttings contained in the fluid stream towards said first orifice.
 4. A device according to claim 3, wherein said means for dividing comprise deviating means enhancing the action of the centrifugal force produced by the rotation of the bit.
 5. A device according to claim 1, comprising the combination of a distributing piston axially isolating said Venturi from the flushing fluid flow, said piston comprising a first series of channels communicating, in a first position of said piston, with feeding ducts for said ejector and a second series of channels which, in a second position of said piston, directly interconnect said Venturi, at the upper part thereof, with the feed of flushing fluid, the switching from said first to said second position being controlled by means for obstructing the channels of said first series.
 6. A device according to claim 5, in which said means for obstructing the channels of said first series consists of a ball placed into the drill string.
 7. A device according to claim 3, wherein said means for dividing comprises means adapted to feed said ejector with a stream of flushing fluid having a swirling motion. 